1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2018, Matthew Macy <[email protected]>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 *
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/types.h>
34 #include <sys/systm.h>
35 #include <sys/counter.h>
36 #include <sys/epoch.h>
37 #include <sys/gtaskqueue.h>
38 #include <sys/kernel.h>
39 #include <sys/limits.h>
40 #include <sys/lock.h>
41 #include <sys/malloc.h>
42 #include <sys/mutex.h>
43 #include <sys/pcpu.h>
44 #include <sys/proc.h>
45 #include <sys/sched.h>
46 #include <sys/sx.h>
47 #include <sys/smp.h>
48 #include <sys/sysctl.h>
49 #include <sys/turnstile.h>
50 #include <vm/vm.h>
51 #include <vm/vm_extern.h>
52 #include <vm/vm_kern.h>
53 #include <vm/uma.h>
54
55 #include <ck_epoch.h>
56
57 static MALLOC_DEFINE(M_EPOCH, "epoch", "epoch based reclamation");
58
59 #ifdef __amd64__
60 #define EPOCH_ALIGN CACHE_LINE_SIZE*2
61 #else
62 #define EPOCH_ALIGN CACHE_LINE_SIZE
63 #endif
64
65 TAILQ_HEAD (epoch_tdlist, epoch_tracker);
66 typedef struct epoch_record {
67 ck_epoch_record_t er_record;
68 volatile struct epoch_tdlist er_tdlist;
69 volatile uint32_t er_gen;
70 uint32_t er_cpuid;
71 /* fields above are part of KBI and cannot be modified */
72 struct epoch_context er_drain_ctx;
73 struct epoch *er_parent;
74 } __aligned(EPOCH_ALIGN) *epoch_record_t;
75
76 struct epoch {
77 struct ck_epoch e_epoch __aligned(EPOCH_ALIGN);
78 epoch_record_t e_pcpu_record;
79 int e_idx;
80 int e_flags;
81 /* fields above are part of KBI and cannot be modified */
82 struct sx e_drain_sx;
83 struct mtx e_drain_mtx;
84 volatile int e_drain_count;
85 };
86
87 /* arbitrary --- needs benchmarking */
88 #define MAX_ADAPTIVE_SPIN 100
89 #define MAX_EPOCHS 64
90
91 CTASSERT(sizeof(ck_epoch_entry_t) == sizeof(struct epoch_context));
92 SYSCTL_NODE(_kern, OID_AUTO, epoch, CTLFLAG_RW, 0, "epoch information");
93 SYSCTL_NODE(_kern_epoch, OID_AUTO, stats, CTLFLAG_RW, 0, "epoch stats");
94
95 /* Stats. */
96 static counter_u64_t block_count;
97
98 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, nblocked, CTLFLAG_RW,
99 &block_count, "# of times a thread was in an epoch when epoch_wait was called");
100 static counter_u64_t migrate_count;
101
102 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, migrations, CTLFLAG_RW,
103 &migrate_count, "# of times thread was migrated to another CPU in epoch_wait");
104 static counter_u64_t turnstile_count;
105
106 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, ncontended, CTLFLAG_RW,
107 &turnstile_count, "# of times a thread was blocked on a lock in an epoch during an epoch_wait");
108 static counter_u64_t switch_count;
109
110 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, switches, CTLFLAG_RW,
111 &switch_count, "# of times a thread voluntarily context switched in epoch_wait");
112 static counter_u64_t epoch_call_count;
113
114 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_calls, CTLFLAG_RW,
115 &epoch_call_count, "# of times a callback was deferred");
116 static counter_u64_t epoch_call_task_count;
117
118 SYSCTL_COUNTER_U64(_kern_epoch_stats, OID_AUTO, epoch_call_tasks, CTLFLAG_RW,
119 &epoch_call_task_count, "# of times a callback task was run");
120
121 TAILQ_HEAD (threadlist, thread);
122
123 CK_STACK_CONTAINER(struct ck_epoch_entry, stack_entry,
124 ck_epoch_entry_container)
125
126 epoch_t allepochs[MAX_EPOCHS];
127
128 DPCPU_DEFINE(struct grouptask, epoch_cb_task);
129 DPCPU_DEFINE(int, epoch_cb_count);
130
131 static __read_mostly int inited;
132 static __read_mostly int epoch_count;
133 __read_mostly epoch_t global_epoch;
134 __read_mostly epoch_t global_epoch_preempt;
135
136 static void epoch_call_task(void *context __unused);
137 static uma_zone_t pcpu_zone_record;
138
139 static void
epoch_init(void * arg __unused)140 epoch_init(void *arg __unused)
141 {
142 int cpu;
143
144 block_count = counter_u64_alloc(M_WAITOK);
145 migrate_count = counter_u64_alloc(M_WAITOK);
146 turnstile_count = counter_u64_alloc(M_WAITOK);
147 switch_count = counter_u64_alloc(M_WAITOK);
148 epoch_call_count = counter_u64_alloc(M_WAITOK);
149 epoch_call_task_count = counter_u64_alloc(M_WAITOK);
150
151 pcpu_zone_record = uma_zcreate("epoch_record pcpu",
152 sizeof(struct epoch_record), NULL, NULL, NULL, NULL,
153 UMA_ALIGN_PTR, UMA_ZONE_PCPU);
154 CPU_FOREACH(cpu) {
155 GROUPTASK_INIT(DPCPU_ID_PTR(cpu, epoch_cb_task), 0,
156 epoch_call_task, NULL);
157 taskqgroup_attach_cpu(qgroup_softirq,
158 DPCPU_ID_PTR(cpu, epoch_cb_task), NULL, cpu, -1,
159 "epoch call task");
160 }
161 inited = 1;
162 global_epoch = epoch_alloc(0);
163 global_epoch_preempt = epoch_alloc(EPOCH_PREEMPT);
164 }
165 SYSINIT(epoch, SI_SUB_TASKQ + 1, SI_ORDER_FIRST, epoch_init, NULL);
166
167 #if !defined(EARLY_AP_STARTUP)
168 static void
epoch_init_smp(void * dummy __unused)169 epoch_init_smp(void *dummy __unused)
170 {
171 inited = 2;
172 }
173 SYSINIT(epoch_smp, SI_SUB_SMP + 1, SI_ORDER_FIRST, epoch_init_smp, NULL);
174 #endif
175
176 static void
epoch_ctor(epoch_t epoch)177 epoch_ctor(epoch_t epoch)
178 {
179 epoch_record_t er;
180 int cpu;
181
182 epoch->e_pcpu_record = uma_zalloc_pcpu(pcpu_zone_record, M_WAITOK);
183 CPU_FOREACH(cpu) {
184 er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
185 bzero(er, sizeof(*er));
186 ck_epoch_register(&epoch->e_epoch, &er->er_record, NULL);
187 TAILQ_INIT((struct threadlist *)(uintptr_t)&er->er_tdlist);
188 er->er_cpuid = cpu;
189 er->er_parent = epoch;
190 }
191 }
192
193 static void
epoch_adjust_prio(struct thread * td,u_char prio)194 epoch_adjust_prio(struct thread *td, u_char prio)
195 {
196
197 thread_lock(td);
198 sched_prio(td, prio);
199 thread_unlock(td);
200 }
201
202 epoch_t
epoch_alloc(int flags)203 epoch_alloc(int flags)
204 {
205 epoch_t epoch;
206
207 if (__predict_false(!inited))
208 panic("%s called too early in boot", __func__);
209 epoch = malloc(sizeof(struct epoch), M_EPOCH, M_ZERO | M_WAITOK);
210 ck_epoch_init(&epoch->e_epoch);
211 epoch_ctor(epoch);
212 MPASS(epoch_count < MAX_EPOCHS - 2);
213 epoch->e_flags = flags;
214 epoch->e_idx = epoch_count;
215 sx_init(&epoch->e_drain_sx, "epoch-drain-sx");
216 mtx_init(&epoch->e_drain_mtx, "epoch-drain-mtx", NULL, MTX_DEF);
217 allepochs[epoch_count++] = epoch;
218 return (epoch);
219 }
220
221 void
epoch_free(epoch_t epoch)222 epoch_free(epoch_t epoch)
223 {
224
225 epoch_drain_callbacks(epoch);
226 allepochs[epoch->e_idx] = NULL;
227 epoch_wait(global_epoch);
228 uma_zfree_pcpu(pcpu_zone_record, epoch->e_pcpu_record);
229 mtx_destroy(&epoch->e_drain_mtx);
230 sx_destroy(&epoch->e_drain_sx);
231 free(epoch, M_EPOCH);
232 }
233
234 static epoch_record_t
epoch_currecord(epoch_t epoch)235 epoch_currecord(epoch_t epoch)
236 {
237
238 return (zpcpu_get_cpu(epoch->e_pcpu_record, curcpu));
239 }
240
241 #define INIT_CHECK(epoch) \
242 do { \
243 if (__predict_false((epoch) == NULL)) \
244 return; \
245 } while (0)
246
247 void
epoch_enter_preempt(epoch_t epoch,epoch_tracker_t et)248 epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et)
249 {
250 struct epoch_record *er;
251 struct thread *td;
252
253 MPASS(cold || epoch != NULL);
254 INIT_CHECK(epoch);
255 MPASS(epoch->e_flags & EPOCH_PREEMPT);
256 #ifdef EPOCH_TRACKER_DEBUG
257 et->et_magic_pre = EPOCH_MAGIC0;
258 et->et_magic_post = EPOCH_MAGIC1;
259 #endif
260 td = curthread;
261 et->et_td = td;
262 td->td_epochnest++;
263 critical_enter();
264 sched_pin();
265
266 td->td_pre_epoch_prio = td->td_priority;
267 er = epoch_currecord(epoch);
268 TAILQ_INSERT_TAIL(&er->er_tdlist, et, et_link);
269 ck_epoch_begin(&er->er_record, &et->et_section);
270 critical_exit();
271 }
272
273 void
epoch_enter(epoch_t epoch)274 epoch_enter(epoch_t epoch)
275 {
276 struct thread *td;
277 epoch_record_t er;
278
279 MPASS(cold || epoch != NULL);
280 INIT_CHECK(epoch);
281 td = curthread;
282
283 td->td_epochnest++;
284 critical_enter();
285 er = epoch_currecord(epoch);
286 ck_epoch_begin(&er->er_record, NULL);
287 }
288
289 void
epoch_exit_preempt(epoch_t epoch,epoch_tracker_t et)290 epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et)
291 {
292 struct epoch_record *er;
293 struct thread *td;
294
295 INIT_CHECK(epoch);
296 td = curthread;
297 critical_enter();
298 sched_unpin();
299 MPASS(td->td_epochnest);
300 td->td_epochnest--;
301 er = epoch_currecord(epoch);
302 MPASS(epoch->e_flags & EPOCH_PREEMPT);
303 MPASS(et != NULL);
304 MPASS(et->et_td == td);
305 #ifdef EPOCH_TRACKER_DEBUG
306 MPASS(et->et_magic_pre == EPOCH_MAGIC0);
307 MPASS(et->et_magic_post == EPOCH_MAGIC1);
308 et->et_magic_pre = 0;
309 et->et_magic_post = 0;
310 #endif
311 #ifdef INVARIANTS
312 et->et_td = (void*)0xDEADBEEF;
313 #endif
314 ck_epoch_end(&er->er_record, &et->et_section);
315 TAILQ_REMOVE(&er->er_tdlist, et, et_link);
316 er->er_gen++;
317 if (__predict_false(td->td_pre_epoch_prio != td->td_priority))
318 epoch_adjust_prio(td, td->td_pre_epoch_prio);
319 critical_exit();
320 }
321
322 void
epoch_exit(epoch_t epoch)323 epoch_exit(epoch_t epoch)
324 {
325 struct thread *td;
326 epoch_record_t er;
327
328 INIT_CHECK(epoch);
329 td = curthread;
330 MPASS(td->td_epochnest);
331 td->td_epochnest--;
332 er = epoch_currecord(epoch);
333 ck_epoch_end(&er->er_record, NULL);
334 critical_exit();
335 }
336
337 /*
338 * epoch_block_handler_preempt() is a callback from the CK code when another
339 * thread is currently in an epoch section.
340 */
341 static void
epoch_block_handler_preempt(struct ck_epoch * global __unused,ck_epoch_record_t * cr,void * arg __unused)342 epoch_block_handler_preempt(struct ck_epoch *global __unused,
343 ck_epoch_record_t *cr, void *arg __unused)
344 {
345 epoch_record_t record;
346 struct thread *td, *owner, *curwaittd;
347 struct epoch_tracker *tdwait;
348 struct turnstile *ts;
349 struct lock_object *lock;
350 int spincount, gen;
351 int locksheld __unused;
352
353 record = __containerof(cr, struct epoch_record, er_record);
354 td = curthread;
355 locksheld = td->td_locks;
356 spincount = 0;
357 counter_u64_add(block_count, 1);
358 /*
359 * We lost a race and there's no longer any threads
360 * on the CPU in an epoch section.
361 */
362 if (TAILQ_EMPTY(&record->er_tdlist))
363 return;
364
365 if (record->er_cpuid != curcpu) {
366 /*
367 * If the head of the list is running, we can wait for it
368 * to remove itself from the list and thus save us the
369 * overhead of a migration
370 */
371 gen = record->er_gen;
372 thread_unlock(td);
373 /*
374 * We can't actually check if the waiting thread is running
375 * so we simply poll for it to exit before giving up and
376 * migrating.
377 */
378 do {
379 cpu_spinwait();
380 } while (!TAILQ_EMPTY(&record->er_tdlist) &&
381 gen == record->er_gen &&
382 spincount++ < MAX_ADAPTIVE_SPIN);
383 thread_lock(td);
384 /*
385 * If the generation has changed we can poll again
386 * otherwise we need to migrate.
387 */
388 if (gen != record->er_gen)
389 return;
390 /*
391 * Being on the same CPU as that of the record on which
392 * we need to wait allows us access to the thread
393 * list associated with that CPU. We can then examine the
394 * oldest thread in the queue and wait on its turnstile
395 * until it resumes and so on until a grace period
396 * elapses.
397 *
398 */
399 counter_u64_add(migrate_count, 1);
400 sched_bind(td, record->er_cpuid);
401 /*
402 * At this point we need to return to the ck code
403 * to scan to see if a grace period has elapsed.
404 * We can't move on to check the thread list, because
405 * in the meantime new threads may have arrived that
406 * in fact belong to a different epoch.
407 */
408 return;
409 }
410 /*
411 * Try to find a thread in an epoch section on this CPU
412 * waiting on a turnstile. Otherwise find the lowest
413 * priority thread (highest prio value) and drop our priority
414 * to match to allow it to run.
415 */
416 TAILQ_FOREACH(tdwait, &record->er_tdlist, et_link) {
417 /*
418 * Propagate our priority to any other waiters to prevent us
419 * from starving them. They will have their original priority
420 * restore on exit from epoch_wait().
421 */
422 curwaittd = tdwait->et_td;
423 if (!TD_IS_INHIBITED(curwaittd) && curwaittd->td_priority > td->td_priority) {
424 critical_enter();
425 thread_unlock(td);
426 thread_lock(curwaittd);
427 sched_prio(curwaittd, td->td_priority);
428 thread_unlock(curwaittd);
429 thread_lock(td);
430 critical_exit();
431 }
432 if (TD_IS_INHIBITED(curwaittd) && TD_ON_LOCK(curwaittd) &&
433 ((ts = curwaittd->td_blocked) != NULL)) {
434 /*
435 * We unlock td to allow turnstile_wait to reacquire
436 * the thread lock. Before unlocking it we enter a
437 * critical section to prevent preemption after we
438 * reenable interrupts by dropping the thread lock in
439 * order to prevent curwaittd from getting to run.
440 */
441 critical_enter();
442 thread_unlock(td);
443
444 if (turnstile_lock(ts, &lock, &owner)) {
445 if (ts == curwaittd->td_blocked) {
446 MPASS(TD_IS_INHIBITED(curwaittd) &&
447 TD_ON_LOCK(curwaittd));
448 critical_exit();
449 turnstile_wait(ts, owner,
450 curwaittd->td_tsqueue);
451 counter_u64_add(turnstile_count, 1);
452 thread_lock(td);
453 return;
454 }
455 turnstile_unlock(ts, lock);
456 }
457 thread_lock(td);
458 critical_exit();
459 KASSERT(td->td_locks == locksheld,
460 ("%d extra locks held", td->td_locks - locksheld));
461 }
462 }
463 /*
464 * We didn't find any threads actually blocked on a lock
465 * so we have nothing to do except context switch away.
466 */
467 counter_u64_add(switch_count, 1);
468 mi_switch(SW_VOL | SWT_RELINQUISH, NULL);
469
470 /*
471 * Release the thread lock while yielding to
472 * allow other threads to acquire the lock
473 * pointed to by TDQ_LOCKPTR(td). Else a
474 * deadlock like situation might happen. (HPS)
475 */
476 thread_unlock(td);
477 thread_lock(td);
478 }
479
480 void
epoch_wait_preempt(epoch_t epoch)481 epoch_wait_preempt(epoch_t epoch)
482 {
483 struct thread *td;
484 int was_bound;
485 int old_cpu;
486 int old_pinned;
487 u_char old_prio;
488 int locks __unused;
489
490 MPASS(cold || epoch != NULL);
491 INIT_CHECK(epoch);
492 td = curthread;
493 #ifdef INVARIANTS
494 locks = curthread->td_locks;
495 MPASS(epoch->e_flags & EPOCH_PREEMPT);
496 if ((epoch->e_flags & EPOCH_LOCKED) == 0)
497 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
498 "epoch_wait() can be long running");
499 KASSERT(!in_epoch(epoch), ("epoch_wait_preempt() called in the middle "
500 "of an epoch section of the same epoch"));
501 #endif
502 thread_lock(td);
503 DROP_GIANT();
504
505 old_cpu = PCPU_GET(cpuid);
506 old_pinned = td->td_pinned;
507 old_prio = td->td_priority;
508 was_bound = sched_is_bound(td);
509 sched_unbind(td);
510 td->td_pinned = 0;
511 sched_bind(td, old_cpu);
512
513 ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler_preempt,
514 NULL);
515
516 /* restore CPU binding, if any */
517 if (was_bound != 0) {
518 sched_bind(td, old_cpu);
519 } else {
520 /* get thread back to initial CPU, if any */
521 if (old_pinned != 0)
522 sched_bind(td, old_cpu);
523 sched_unbind(td);
524 }
525 /* restore pinned after bind */
526 td->td_pinned = old_pinned;
527
528 /* restore thread priority */
529 sched_prio(td, old_prio);
530 thread_unlock(td);
531 PICKUP_GIANT();
532 KASSERT(td->td_locks == locks,
533 ("%d residual locks held", td->td_locks - locks));
534 }
535
536 static void
epoch_block_handler(struct ck_epoch * g __unused,ck_epoch_record_t * c __unused,void * arg __unused)537 epoch_block_handler(struct ck_epoch *g __unused, ck_epoch_record_t *c __unused,
538 void *arg __unused)
539 {
540 cpu_spinwait();
541 }
542
543 void
epoch_wait(epoch_t epoch)544 epoch_wait(epoch_t epoch)
545 {
546
547 MPASS(cold || epoch != NULL);
548 INIT_CHECK(epoch);
549 MPASS(epoch->e_flags == 0);
550 critical_enter();
551 ck_epoch_synchronize_wait(&epoch->e_epoch, epoch_block_handler, NULL);
552 critical_exit();
553 }
554
555 void
epoch_call(epoch_t epoch,epoch_context_t ctx,void (* callback)(epoch_context_t))556 epoch_call(epoch_t epoch, epoch_context_t ctx, void (*callback) (epoch_context_t))
557 {
558 epoch_record_t er;
559 ck_epoch_entry_t *cb;
560
561 cb = (void *)ctx;
562
563 MPASS(callback);
564 /* too early in boot to have epoch set up */
565 if (__predict_false(epoch == NULL))
566 goto boottime;
567 #if !defined(EARLY_AP_STARTUP)
568 if (__predict_false(inited < 2))
569 goto boottime;
570 #endif
571
572 critical_enter();
573 *DPCPU_PTR(epoch_cb_count) += 1;
574 er = epoch_currecord(epoch);
575 ck_epoch_call(&er->er_record, cb, (ck_epoch_cb_t *)callback);
576 critical_exit();
577 return;
578 boottime:
579 callback(ctx);
580 }
581
582 static void
epoch_call_task(void * arg __unused)583 epoch_call_task(void *arg __unused)
584 {
585 ck_stack_entry_t *cursor, *head, *next;
586 ck_epoch_record_t *record;
587 epoch_record_t er;
588 epoch_t epoch;
589 ck_stack_t cb_stack;
590 int i, npending, total;
591
592 ck_stack_init(&cb_stack);
593 critical_enter();
594 epoch_enter(global_epoch);
595 for (total = i = 0; i < epoch_count; i++) {
596 if (__predict_false((epoch = allepochs[i]) == NULL))
597 continue;
598 er = epoch_currecord(epoch);
599 record = &er->er_record;
600 if ((npending = record->n_pending) == 0)
601 continue;
602 ck_epoch_poll_deferred(record, &cb_stack);
603 total += npending - record->n_pending;
604 }
605 epoch_exit(global_epoch);
606 *DPCPU_PTR(epoch_cb_count) -= total;
607 critical_exit();
608
609 counter_u64_add(epoch_call_count, total);
610 counter_u64_add(epoch_call_task_count, 1);
611
612 head = ck_stack_batch_pop_npsc(&cb_stack);
613 for (cursor = head; cursor != NULL; cursor = next) {
614 struct ck_epoch_entry *entry =
615 ck_epoch_entry_container(cursor);
616
617 next = CK_STACK_NEXT(cursor);
618 entry->function(entry);
619 }
620 }
621
622 int
in_epoch_verbose(epoch_t epoch,int dump_onfail)623 in_epoch_verbose(epoch_t epoch, int dump_onfail)
624 {
625 struct epoch_tracker *tdwait;
626 struct thread *td;
627 epoch_record_t er;
628
629 td = curthread;
630 if (td->td_epochnest == 0)
631 return (0);
632 if (__predict_false((epoch) == NULL))
633 return (0);
634 critical_enter();
635 er = epoch_currecord(epoch);
636 TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link)
637 if (tdwait->et_td == td) {
638 critical_exit();
639 return (1);
640 }
641 #ifdef INVARIANTS
642 if (dump_onfail) {
643 MPASS(td->td_pinned);
644 printf("cpu: %d id: %d\n", curcpu, td->td_tid);
645 TAILQ_FOREACH(tdwait, &er->er_tdlist, et_link)
646 printf("td_tid: %d ", tdwait->et_td->td_tid);
647 printf("\n");
648 }
649 #endif
650 critical_exit();
651 return (0);
652 }
653
654 int
in_epoch(epoch_t epoch)655 in_epoch(epoch_t epoch)
656 {
657 return (in_epoch_verbose(epoch, 0));
658 }
659
660 static void
epoch_drain_cb(struct epoch_context * ctx)661 epoch_drain_cb(struct epoch_context *ctx)
662 {
663 struct epoch *epoch =
664 __containerof(ctx, struct epoch_record, er_drain_ctx)->er_parent;
665
666 if (atomic_fetchadd_int(&epoch->e_drain_count, -1) == 1) {
667 mtx_lock(&epoch->e_drain_mtx);
668 wakeup(epoch);
669 mtx_unlock(&epoch->e_drain_mtx);
670 }
671 }
672
673 void
epoch_drain_callbacks(epoch_t epoch)674 epoch_drain_callbacks(epoch_t epoch)
675 {
676 epoch_record_t er;
677 struct thread *td;
678 int was_bound;
679 int old_pinned;
680 int old_cpu;
681 int cpu;
682
683 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,
684 "epoch_drain_callbacks() may sleep!");
685
686 /* too early in boot to have epoch set up */
687 if (__predict_false(epoch == NULL))
688 return;
689 #if !defined(EARLY_AP_STARTUP)
690 if (__predict_false(inited < 2))
691 return;
692 #endif
693 DROP_GIANT();
694
695 sx_xlock(&epoch->e_drain_sx);
696 mtx_lock(&epoch->e_drain_mtx);
697
698 td = curthread;
699 thread_lock(td);
700 old_cpu = PCPU_GET(cpuid);
701 old_pinned = td->td_pinned;
702 was_bound = sched_is_bound(td);
703 sched_unbind(td);
704 td->td_pinned = 0;
705
706 CPU_FOREACH(cpu)
707 epoch->e_drain_count++;
708 CPU_FOREACH(cpu) {
709 er = zpcpu_get_cpu(epoch->e_pcpu_record, cpu);
710 sched_bind(td, cpu);
711 epoch_call(epoch, &er->er_drain_ctx, &epoch_drain_cb);
712 }
713
714 /* restore CPU binding, if any */
715 if (was_bound != 0) {
716 sched_bind(td, old_cpu);
717 } else {
718 /* get thread back to initial CPU, if any */
719 if (old_pinned != 0)
720 sched_bind(td, old_cpu);
721 sched_unbind(td);
722 }
723 /* restore pinned after bind */
724 td->td_pinned = old_pinned;
725
726 thread_unlock(td);
727
728 while (epoch->e_drain_count != 0)
729 msleep(epoch, &epoch->e_drain_mtx, PZERO, "EDRAIN", 0);
730
731 mtx_unlock(&epoch->e_drain_mtx);
732 sx_xunlock(&epoch->e_drain_sx);
733
734 PICKUP_GIANT();
735 }
736
737 /* for binary compatibility */
738
739 struct epoch_tracker_KBI {
740 void *datap[3];
741 #ifdef EPOCH_TRACKER_DEBUG
742 int datai[5];
743 #else
744 int datai[1];
745 #endif
746 } __aligned(sizeof(void *));
747
748 CTASSERT(sizeof(struct epoch_tracker_KBI) >= sizeof(struct epoch_tracker));
749
750 void
epoch_enter_preempt_KBI(epoch_t epoch,epoch_tracker_t et)751 epoch_enter_preempt_KBI(epoch_t epoch, epoch_tracker_t et)
752 {
753 epoch_enter_preempt(epoch, et);
754 }
755
756 void
epoch_exit_preempt_KBI(epoch_t epoch,epoch_tracker_t et)757 epoch_exit_preempt_KBI(epoch_t epoch, epoch_tracker_t et)
758 {
759 epoch_exit_preempt(epoch, et);
760 }
761
762 void
epoch_enter_KBI(epoch_t epoch)763 epoch_enter_KBI(epoch_t epoch)
764 {
765 epoch_enter(epoch);
766 }
767
768 void
epoch_exit_KBI(epoch_t epoch)769 epoch_exit_KBI(epoch_t epoch)
770 {
771 epoch_exit(epoch);
772 }
773